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Old 17th January 2006, 09:33 AM   #1
DolbyR is offline DolbyR  Finland
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Default Fake Law Log Pot

ive heard of some resistors tweaks to make from a Lin a pot, a Log one. Is it possible also to make a fake reverse Log pot from a linear one? And how would this happen?
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Old 17th January 2006, 09:57 AM   #2
Did it Himself
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Just connect resistor wiper to input instead of wiper to ground
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Old 17th January 2006, 09:59 AM   #3
DolbyR is offline DolbyR  Finland
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so no additional resistor is needed to the pot? or a resistor from wiper to input?
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Old 17th January 2006, 12:49 PM   #4
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See here:
http://www.geofex.com/Article_Folder...s/potscret.htm

Like the other guy says, politics aside, google is a wonderful thing...

If you have a spreadsheet program you can easily calculate and plot the curve that you will get- it's all Ohms law...

I_F
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Old 17th January 2006, 12:55 PM   #5
sam9 is offline sam9  United States
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Go to http://sound.westhost.com and look up Project 01. Not only can you make a linear pot behave like a log pot, it is argued that the results are moe accurate than a real log pot. This may be especially true with a double-ganged pot.

BTW, I only buy linear pots any more. It's not really all that big a deal in normal use but I definately discern that the "fake" log-pots respond more evenly than "real" ones.
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Old 17th January 2006, 02:06 PM   #6
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He knows about law faking lin to get a log pot His question was how do you make an antilog pot.
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Old 17th January 2006, 02:34 PM   #7
Bobken is offline Bobken  United Kingdom
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Hi,

Please note that any 'reverse log' pot made in this way (law-faking) will only work as a full 3 terminal voltage-divider arrangement.

It doesn't work properly as a simple two terminal 'variable resistor' arrangement as the change in resistance which is more pronounced per unit of rotation at one extreme, will be at the 'wrong end' of rotation, unfortunately.

I know because I tried it out quite recently, myself, much to my disappointment, and when I subsequently made some suitable calculations of the parallel resistances involved at different points of rotation, it was quite clear to me why this is the case.

Also, it cannot simply be corrected by reversing the connections for a two terminal arrangement, either, as this makes no difference, of course.
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Old 17th January 2006, 10:55 PM   #8
00940 is offline 00940  Belgium
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http://tangentsoft.net/audio/atten.html worth reading.
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